Magic - When using sulfurous springs...?

Question

Do I physically need the land cards in my hand to use its tap effect? And does the tap effect also come into effect when I tap it just to use mana?

Answer 1

Sulfurous Springs says that you tap it to add Black or Red to your mana pool and it does 1 damage to you.  Or you can tap it for colorless and have it do no damage to you.

When you tap it for colored mana, you do not put a swamp or mountain into play from your hand.  It acts like a mountain or swamp.  It will deposit the mana into your mana pool for you to use.  You do not have to have cards in hand to use it.  Just remember that you do not have to tap it for colored mana each time.  Only when you need it.  You can use it for colorless mana anytime and it won't hurt you.  Also, remember that you have to use the mana on the current phase or else it will burn you for 1 damage for each unused mana.  You do not have to use all your lands on each turn.  You only need to use the lands that you will need to use.

Answer 2

Dual pain lands, like Sulfurous springs allow you to add mana of the color you need, but at a price.  Sulfurous Springs will give you a generic mana for your use, or if you really need a black or red mana, it will allow you to tap it for the black or red mana, but will do one point of damage to you.  These types of lands are exceptionally helpful for when you need that specific color in a two color deck (for Sulfurous Springs, specifically black or red) or you need a second color of the type indicated on the land.  This is one of the reasons that most lands that can produce 2 colors of mana are worth a lot of money, ranging from $4.00 - $20.00 per card depending on the land and the deck it can be played in.  Example, Hallowed Fountains used to go for $18.00, Reflecting Pool also went for $12-$16, but since Graven Cairns had never been in a top 8 or PTQ winning deck, it goes for about $4.00.

Hope all this helps.